Defence in Depth: Beyond Roman Grand Strategy

Abstract

Many scholars have struggled to define and characterize the Late Roman Empire's defensive policy, in order to understand the underlying causes of the defensive deterioration, which some have seen as a factor in the fall of the Western Roman Empire. In 1976 American theorist Edward Luttwak published his Grand Strategy of the Roman Empire, which defined the defensive evolution of the third century as Rome's pragmatic shift towards a policy of 'defence in depth', whereby the military would abandon their traditionally static frontier security policy in exchange for a fundamentally elastic one. Was the Empire capable of designing a ‘grand strategy’, and did it have the command‐control capacity for such endeavours? Did the Romans commit a devastating strategic blunder by withdrawing the military presence that had for so long subdued the will of the migratory peoples in the periphery? Critics have accused this 'defence in depth' hypothesis of failing to factor in strong literary and archaeological evidence that contests the theory, while relying heavily on modern military concepts and terminology. Ongoing research has indicated that while this Late Roman strategy was executed in various forms throughout the empire, the essential approach of the military was dictated through a well defined operational framework. This paper asserts that Roman defence in depth was a consciously adopted policy of the Roman state and addresses some of the main criticisms presented by scholars who refute the possibility of this system's existence.